Preview of NWS' New Version of Forecast
This preview is not operational and should not be used for support decisions.

Area Forecast Discussion (AFD)

Issued by Philadelphia/Mt Holly (PHI)

FXUS61 KPHI 230822

Area Forecast Discussion
National Weather Service Mount Holly NJ
422 AM EDT Mon Sep 23 2019

A cold front will approach today and then move across the 
region tonight. High pressure returns for the mid-week period, 
followed by another cold front late Thursday and Thursday night.
High pressure builds back into the Northeast for the end of the
week into next weekend. 


Expect another warm day today as high pressure finally starts 
pushing to the east. A surface trough will bring a cold front 
through during the late afternoon but not until temp warm up 
again into the upper 80s to near 90. When the front swings 
through expect showers to move into the Poconos first and then 
through the 95 corridor. The best chance for showers will be 
along and ahead of the front as we should destabilize briefly 
allow for some modest instability. I've kept the idea of some 
isolated rumbles of thunder generally from Philly northwards.

As for the rest of this morning, patchy fog will likely continue
to build into the favored locations. VAD wind profiles show 
modest boundary layer flow so expect the best chance for some 
light ground fog near the protected river basins and in more 
rural locations. Temps will bottom our in the mid 60s shortly 
before warming quickly this morning. As the cape breaks this 
afternoon expect it to become fairly breezy with winds gusts up 
to 20 mph generally out of the southwest. Winds will be a fair 
bit stronger just along the coastline with gusts up to 25-30mph 
along the waters. Hope you get to enjoy your day!


Overnight Monday should be a fairly pleasant evening. Temps 
behind the cold front will drop into the upper 50s to low 60s 
and the rainfall will be exiting to the east. Clouds will be 
clearing from west to east across the region as high pressure 
starts building back across the Mid-Atlantic setting up for a 
nice week!



Tuesday through Wednesday night...

Low pressure with its associated cold front will continue to slowly 
move off to the east through Tuesday while high pressure sits across 
the Ohio Valley. This will keep the area in a cooler, dry NW flow 
with temperatures a good 10 degrees or so cooler compared to Monday. 
Most of the area should see mainly sunny skies but there will be a 
fair bit of Cu developing across the Poconos into NW NJ. Highs will 
be mainly in the 75-80 range except a bit cooler in these northern 
areas where it will be in the upper 60s to low 70s. 

High pressure drifts east towards the region Tuesday night resulting 
in mainly clear skies and light winds. This will allow for good 
radiational cooling conditions so lows will be comfortably 
cool...generally in the mid to upper 50s with some upper 40s over 
the southern Poconos. This will be followed by sunshine, light west 
winds and seasonably warm temperatures for Wednesday under dominant 
high pressure with highs generally in the 70s to around 80. 

By Wednesday night, high pressure moves eastward off the coast with 
the flow turning light SW ahead of the next approaching cold front. 
This will allow for somewhat warmer overnight lows under continuing 
mainly clear skies. Lows will be mainly in the 50s to low 60s, 
coolest in the southern Poconos and warmest over the Delmarva NE 
through the Philly urban area. 

Thursday through Sunday...

In the big picture, large scale upper level ridging looks to 
continue dominating in the east bringing generally fair weather with 
seasonably warm temperatures. That said, there is some uncertainty 
in the forecast by next weekend as the GFS brings a cold front 
through the area flattening the ridge while the ECMWF maintains 
strong ridging. 

To start the period Thursday, a cold front approaches and then moves 
through the area late day. However this still looks to be largely a 
dry front as most of upper level energy associated with a 
progressive upper trough will be to our north. So for this reason, 
expect an overall partly to mostly sunny day with highs mainly in 
the low to mid 80s along with moderate humidity levels. Exception 
will be the southern Poconos where it will be in the 70s. 

Cold front quickly sweeps east of the region Thursday night with 
high pressure and strong ridging aloft moving back in by Friday. 
This will bring more sunshine with seasonably warm temperatures and 
low humidity. Beyond this time, as mentioned above, some uncertainty 
in the forecast for next weekend. GFS brings a cold front through 
from north to south Saturday along with some scattered showers and 
then stalls this front near or just south of the area Sunday as high 
pressure moves back in from the north. ECMWF maintains strong ridge 
keeping conditions warm and dry. At this point, made little change 
from previous forecast and keep conditions mainly dry for next 
weekend with highs mainly in the 80s. However if GFS solution ends 
up coming to fruition it could be cooler and a little bit unsettled 
with a few showers around at times but not a washout. 

The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, 
KMIV, KACY and surrounding areas.

Rest of Tonight...Mainly VFR. However, some patchy fog may 
develop late. Winds light and variable. Low confidence on fog 

Monday...Any fog early in the day will dissipate rapidly. 
Mainly VFR with winds increasing from the south/southwest around
10 kt, possibly with some gusts 15-20 kt (especially at 
PHL/ACY). Scattered light rain showers will start to move
through late in the afternoon into the evening as a cold front
moves through. High confidence.


Tuesday and Tuesday night...VFR. Northwest winds 10-15 knots 
during the day, then around 5 knots or less overnight.

Wednesday and Wednesday night...VFR. Westerly winds around 5 
knots becoming southwesterly less than 5 knots.

Thursday...Mostly VFR. Cold front expected to move across the 
area during the afternoon, but likely to remain dry for most of 
the area except northeast Pennsylvania and northern New Jersey. 
Wind shift from southwest to west, then northwest behind the 
front and may gust 15-20 knots in the afternoon.

Thursday night...VFR conditions expected. Northwest winds 5-10 

Friday-Friday night...VFR conditions expected. Light and 
variable winds early, becoming southerly around knots late in 
the day and overnight.


South to southwest winds 10 to 20 kt are expected to continue 
through Monday with gusts approaching 25 kt by afternoon. Expect
winds to continue into the overnight hours for the Atlantic 
waters, with winds expected to be somewhat lower on Delaware 

In addition, seas will increase to around or slightly above 5 
feet by afternoon. As a result, have issued a small craft 
advisory beginning at 9 am Monday for the Atlantic waters.


Tuesday...Conditions expected to be sub SCA with NW winds 10-15
knots and seas 3-5 feet. 

Wednesday...sub-SCA conditions expected with NW winds around 
10 knots turning southwesterly through the afternoon and seas 
from 3 to 5 feet. 

Thursday...sub-SCA conditions expected with southwesterly winds
continuing from 10 to 15 knots and gusts to 20 knots. Seas 
building to 2 to 4 feet.

Friday...sub-SCA conditions expected with northeasterly winds 
from 5 to 10 knots turning easterly by the afternoon. Seas to 
sit from 1 to 3 feet.


There is a HIGH risk for the development of dangerous rip 
currents at New Jersey and Delaware beaches on Monday due to 
increasing winds and seas. A Rip Current Statement has been 
issued for this risk.


NJ...High Rip Current Risk from 6 AM EDT this morning through this 
     evening for NJZ014-024>026.
DE...High Rip Current Risk from 6 AM EDT this morning through this 
     evening for DEZ004.
MARINE...Small Craft Advisory from 10 AM this morning to 6 AM EDT 
     Tuesday for ANZ450>455.


Near Term...Deal
Short Term...Deal 
Long Term...Fitzsimmons